The paper contrastes and analysies the marking for the coarse degree ...

本旧标准中表面粗糙度的标注进行比分析。

This paper introduces studying and using process of new type polyurethane sealing element,contrastes with similar import sealing element.

介绍型聚胺脂密封件的研究开发和使用过程,并与进密封件进行比,有一定的实用价值。